Device for polishing peripheral edge of semiconductor wafer

ABSTRACT

A device for polishing the peripheral edge part of a semiconductor wafer includes a wafer stage for holding the wafer, a wafer stage unit including devices for rotating the wafer stage, causing the wafer stage to undergo a rotary reciprocating motion within the same plane as the surface of the wafer stage, and moving the wafer stage parallel to the surface, a notch polishing part for polishing the notch on the wafer and a bevel polishing part for polishing the beveled part of the wafer. Pure water is supplied to the wafer to prevent it from becoming dry as it is transported from the notch polishing part to the bevel polishing part.

This application is a continuation of International Application No.PCT/JP2006/308492 filed Apr. 18, 2006, that was amended on Sep. 14, 2006and claims priority on Japanese Patent Application 2005-121464 filedApr. 19, 2005.

TECHNICAL FIELD

This invention relates to a device for polishing the peripheral edgepart (including the notch and the beveled part) of a semiconductorwafer.

BACKGROUND ART

The peripheral edge part of a semiconductor wafer is conventionallypolished by independently using a device for polishing the notch part(as disclosed in Japanese Patent Publication Tokkai 9-85599) and anotherdevice for polishing the beveled part (as disclosed in Japanese PatentPublications Tokkai 7-164301 and 8-174399). The polishing of theperipheral part is carried out by a so-called wet method whereby apolishing liquid in a slurry form obtained by dispersing abradingparticles in water or a water-based reactive liquid is supplied to thetarget part to be polished (such as the notch and/or the beveled part)together with cooling water while a tape made of a woven or non-wovencloth or a foamed body or a tape having a polishing layer with abradingparticles affixed by an adhesive formed on the surface of a plasticmaterial is pressed onto the target part and caused to run.

Such conventional methods have problems because the notch and thebeveled part of a semiconductor wafer are polished independently suchthat it takes too long to transport the wafer between these two devicesand this requires a large space for the equipment. There is also theproblem of the semiconductor wafer becoming dry while being transported,adversely affecting the yield of device wafers.

The positioning of a semiconductor wafer on the wafer stage in eachpolishing device is carried out by means of a pair of chuck handles of arobot for transporting wafers but since a plurality of cylinders areused for improved accuracy in the positioning, a large space is requiredfor the equipment. Since air cylinders are used for the purpose,furthermore, an error on the order of 0.5 mm arises in the positioning.There is still another problem that an excessive grasping force isapplied on the peripheral edge of the wafer and tends to damage the edgeportion of the wafer.

The semiconductor wafer is adsorbed to the wafer stage by vacuum. Whenthis semiconductor wafer is removed from the wafer stage, the wafer isreleased from this condition of vacuum adsorption as the wafer isgrasped on its peripheral parts by the pair of chuck handles of therobot and lifted up. This means that a large releasing force is requiredfor removing the semiconductor wafer from the wafer stage and this mustbe exerted instantaneously on the semiconductor wafer. This gives riseto the problem of deforming or damaging the semiconductor wafer.

According to prior art technologies, a polishing tape is supplied from asupply roller during the polishing process by changing the torque valueof a motor for the supply of the tape according to the outer diameter ofthe tape (that is, the amount of the tape still remaining on the supplyroll) such that the tension of the tape pressed onto the target portionto be polished can be adjusted. Since the outer diameter of the tape isdetermined by the presence or absence of light from a light emitterreceived by a plurality (usually eight) of sensors of a light receivingpart arranged at the side of the tape supply roll, the torque value ofthe motor changes in a stepwise manner, giving rise to the problem ofthe tension in the tape not being constant.

DISCLOSURE OF INVENTION

It is therefore an object of this invention, which relates to theprocessing of the peripheral part a semiconductor wafer, to provide adevice for polishing the notch and the beveled part of a semiconductorwafer efficiently within a single device.

It is another object of this invention to provide such a device withwhich the polishing time can be shortened and the space required for theapparatus can be reduced.

It is a third object of this invention to provide such a device capableof positioning a semiconductor wafer accurately on a wafer stage.

It is a fourth object of this invention to provide such a device capableof easily removing a semiconductor wafer supported by adsorption on thewafer stage.

It is a fifth object of this invention to provide such a device capableof maintaining the tension in the tape constant independent of the outerdiameter of the tape (or its remaining amount on the supply roll) on thepolishing head.

A device according to this invention with which the objects describedabove can be accomplished is for polishing the peripheral edge part of asemiconductor wafer and comprises a wafer stage having a surface forholding the semiconductor wafer, a wafer stage unit including a stagerotating part for rotating the wafer stage and a reciprocating motionpart for causing the wafer stage to undergo a rotary reciprocatingmotion within the same plane as the surface of the wafer stage, a stagemoving part for moving the wafer stage parallel to the surface, and twoor more polishing parts for polishing the peripheral edge part of thesemiconductor wafer being held by the wafer stage.

These two or more polishing parts include a notch polishing part forpolishing a notch on the semiconductor wafer held by the wafer stage anda bevel polishing part for polishing beveled part of the semiconductorwafer held by the wafer stage.

The device of the invention further comprises a housing that containsthe wafer stage unit, the polishing parts and the stage moving part andhas a side surface with an opening which can be opened and closed. Thehousing includes two chambers partitioned by a partition plate, one ofthe chambers containing the wafer stage unit and the polishing parts,and the other of the chambers containing the stage moving part.

The device of the invention further comprises a dryness preventing partfor supplying pure water to the semiconductor wafer held by the waferstage.

The device of the invention further comprises a chuck assembly forreceiving the semiconductor wafer transported into the housing, placingthe semiconductor wafer on the wafer stage and delivering thesemiconductor wafer on the wafer stage to a wafer transporting part. Thechuck assembly includes a first chuck hand having two or more knobs, asecond chuck hand having two or more knobs, a chuck opening part foropening and closing the first chuck hand and the second chuck hand, anda chuck moving part for causing the first chuck hand and the secondcheck hand to undergo a reciprocating motion perpendicularly to thesurface of the wafer stage, wherein the knobs contact peripheral partsof the semiconductor wafer when the first chuck hand and the secondchuck hand are closed such that the semiconductor wafer becomes graspedby the first chuck hand and the second chuck hand.

The chuck opening part comprises a ball screw engaging with at least oneof the first and second chuck hands and a servo motor for driving theball screw wherein the first and second chuck hands open and close asthe servo motor is activated.

The device of this invention further comprises a sensor assembly havinga notch detecting part for detecting the position of a notch onsemiconductor wafer being held on the wafer stage by suction. The notchdetecting part includes an optical sensor having a light emitter and alight receiver arranged such that the notch on the semiconductor waferheld by the wafer stage by suction passes between the light emitter andthe light receiver, the optical sensor serving to detect the position ofthe notch by rotating the semiconductor wafer.

Preferably, the sensor assembly includes three optical sensors which arefirst optical sensor, second optical sensor and third optical sensor,the first optical sensor being adapted to detect the position of thenotch when the wafer stage is rotating at a rotational speed within afirst range, the second optical sensor being adapted to detect theposition of the notch when the wafer stage is rotating at a rotationalspeed within a second range that is slower than the first range, and thethird optical sensor being adapted to detect the position of the notchwhen the wafer stage is rotating at a rotational speed within a thirdrange that is slower than the second range.

The sensor assembly further includes a displacement detecting part fordetecting positional displacement in radial direction of thesemiconductor wafer held by the wafer stage by suction, the displacementdetecting part comprising an optical sensor having a light emitter and alight receiver arranged such that the peripheral edge of thesemiconductor wafer held by the wafer stage by suction passes betweenthe light emitter and the light receiver, the optical sensor serving todetect changes in the quantity of light received by the light receiverand to thereby detect a radial displacement of the position of thesemiconductor wafer held by the wafer stage by suction.

Preferably, the third sensor is arranged such that the peripheral edgeincluding the notch of the semiconductor wafer held by the wafer stageby suction passes between the light emitter and the light receiver, thethird optical sensor serving to detect changes in the quantity of lightreceived by the light receiver thereof and to thereby detect a radialdisplacement of the position of the semiconductor wafer held by thewafer stage by suction and to detect the position of the notch of thesemiconductor wafer when the wafer stage is rotating at a rotary speedwithin the third range.

The sensor assembly further comprises a waterproofing part forwaterproofing the sensor assembly.

The notch polishing part comprises a notch polishing head having a firstroller and a second roller arranged parallel to each other with aninterval in between and a tape supplying part including a supply rollhaving a tape wound therearound, a take-up roller for taking up the tapefrom the supply roll through the first and second rollers and a drivingpart for driving the take-up roller for taking up the tape, wherein thetape is adapted to be pressed against the notch while passing betweenthe first roller and the second roller to thereby polish the notch.

The tape comprises a tape-shaped base film of a plastic material havinga polishing layer with abrading particles fastened by a resin binder.

The notch polishing part further includes a mechanism for causing thenotch polishing head to undergo a reciprocating motion perpendicularlyto the semiconductor wafer while the tape is pressed against the notch.

The notch polishing part further includes another mechanism for causingthe notch polishing head to undergo a rotary reciprocating motion aroundthe notch while the tape is pressed against the notch such that bothfront and back surface sides of the notch are polished.

Preferably, the notch polishing part further includes a diameterdetecting part for detecting the outer diameter of the tape remainingwound around the supply roll.

The bevel polishing part comprises a bevel polishing head having acylinder with a contact pad attached to an end and a tape supplying parthaving a supply roll having a tape wound therearound, a take-up rollerfor winding up the tape from the supply roll through the contact pad,and a driving part for driving the take-up roller for winding up thetape, wherein the tape is pressed against the beveled part while passingon the contact pad and thereby polishes the beveled part.

The tape comprises a tape-shaped base film of a plastic material havinga polishing layer with abrading particles fastened by a resin binder.

The bevel polishing part further includes a mechanism for causing thebevel polishing head to undergo a rotary reciprocating motion around thesemiconductor wafer while the tape is pressed against the beveled partsuch that both front and back surface sides of the beveled part arepolished.

The bevel polishing part further includes a diameter detecting part fordetecting the outer diameter of the tape remaining wound around thesupply roll.

The bevel polishing part further includes a displacement detecting partfor detecting displacement of the semiconductor wafer while the beveledpart is being polished, the displacement detecting part comprising adisplacement sensor for detecting change in stretching and shrinking ofthe cylinder serving to compress the tape to the beveled part throughthe contact pad while the semiconductor wafer is being polished.

The device of this invention further comprises a cleaning part formaintaining the interior of the housing clean, the cleaning partcomprising an air inlet through an upper surface of the housing, an airdischarge outlet through a lower side surface of the housing and anexternal pump connected to the air discharge outlet, the air inlet andthe air discharge outlet being arranged such that air flows in throughthe air inlet and flows inside the housing along side surfaces thereof.

The device of this invention further comprises a structure forwaterproofing the other chamber.

Preferably, the partition plate of the device of this invention has anopening, wherein the stage rotating part comprises a first shaftattached to the center on the back of the wafer stage, a support memberrotatably attached to the first shaft and a first motor for rotating thefirst shaft, wherein the reciprocating motion part comprises a secondshaft that is affixed to the support member of the wafer stage at aposition offset from the center of the wafer stage by approximately thedistance of one half of the radius of the semiconductor wafer throughthe opening through said partition plate and a second motor for rotatingthe second shaft, the second shaft being rotatably attached to a shafttable that is hollow and cylindrical, the shaft table having a lowersurface affixed to a support plate below the partition plate and anupper surface supporting the support member by contacting the lowersurface of the support member and the second motor being affixed to thesupport member, and wherein the device further comprises a hollowsemi-spherical waterproofing cover having an upper affixed in aliquid-tight manner to an upper part of the shaft table and a lower partaffixed in a liquid-tight manner around the opening through thepartition plate, the waterproofing cover being made of an elasticmaterial.

Preferably, the waterproofing cover is of a double structure having aninner cover and an outer cover, said device further comprising an airsupplying part for supplying compressed air into a space between saidinner cover and said outer cover.

A method of this invention with which the objects described above can beaccomplished is for polishing peripheral edge part of a semiconductorwafer and comprises holding step of holding the semiconductor wafer by awafer stage by suction and polishing step of polishing the peripheraledge part of the semiconductor wafer supported by the wafer stage bysuction by two or more polishing parts. The polishing step comprisesmoving the wafer stage supporting the semiconductor wafer sequentiallyto each of the two or more polishing parts and causing each of thepolishing parts to polish the peripheral part of the semiconductorwafer.

The method of this invention further comprises dryness preventing stepof supplying pure water to the semiconductor wafer supported by thewafer stage while the semiconductor wafer is being transported betweenthe two or more polishing parts.

The two or more polishing parts include a notch polishing part forpolishing a notch on the semiconductor wafer and a bevel polishing partfor polishing a beveled part of the semiconductor wafer.

Since this invention is constituted as above, the following effects areconducted.

Since a semiconductor wafer is transported between a notch polishinghead and a bevel polishing head by simply moving a wafer stage byoperation of a stage moving part, not only a notch and a beveled part ofa semiconductor wafer can be polished efficiently within a singledevice, but also the polishing time can be shortened and the spacerequired for the apparatus can be reduced.

A semiconductor wafer can be positioned accurately on a wafer stage bythe notch detecting part and the displacement detecting part.

According to this invention, while a semiconductor wafer supported byadsorption on the wafer stage is grasped and lifted up by the chuckhands, this wafer can be easily released from the suction force towardsthe wafer stage by stopping the operation of the vacuum pump when thewafer has been lifted up just a little (0.5 mm-1.0 mm).

Since an optical sensor continuously detects the outer diameter of thetape (or its remaining amount on the supply roll), the tension in thetape can be maintained in constant.

Components of a driving system (the stage moving part) are covered withthe waterproof cover made of an elastic material, and thereby thedriving system in the device can be protected against water.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a plan view of a semiconductor wafer, and FIGS. 1B and 1C areeach a sectional view of its peripheral edge portion.

FIGS. 2A and 2B are together referred to as FIG. 2, FIG. 2A being a planview of a device according to this invention and FIG. 2B showing thereciprocating rotary motion of the semiconductor wafer.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2A.

FIG. 4 is a sectional view taken along line 4-4 of FIG. 2A.

FIGS. 5A and 5B are respectively a plan view of and a side view of thewafer chuck assembly.

FIGS. 6A and 6B are each a plan view of the sensor assembly.

FIGS. 7A and 7B are each a side view of the sensor assembly.

FIG. 8 is a schematic view of the diameter detecting part for detectingthe outer diameter of the tape.

FIG. 9 is a plan view of the wafer stage.

FIG. 10 is a side view of the notch polishing head.

FIG. 11 is a side view of the bevel polishing head.

FIG. 12A is a sectional view of a waterproofing cover of a singlestructure, FIG. 12B is its diagonal view, and FIG. 12C is a sectionalview of a waterproofing cover of a double structure.

FIG. 13A is a plan view of a semiconductor wafer held by the waferstage, and FIG. 13B is a graph for showing the change in the quantity ofreceived light against the angle of rotation of the wafer.

FIGS. 14A, 14B and 14C are each a schematic diagonal view of the notchon the wafer passing below the light emitter of an optical sensor.

BEST MODE FOR CARRYING OUT THE INVENTION

A device according to this invention is for polishing the peripheraledge part of a semiconductor wafer (inclusive of the notch and thebeveled part).

As shown in FIG. 1A, the semiconductor wafer (hereinafter referred tosimply as the wafer) W is a thin disk comprising monocrystalline siliconand a notch N is provided to its periphery for indicating itsorientation, serving as an a reference for positioning the circularlyshaped wafer W inside a semiconductor processing apparatus.

The wafer W may be roughly classified either as a straight type or around type, depending on its cross-sectional shape. A semiconductorwafer of a straight type has a polygonal sectional shape as shown inFIG. 1B, while a semiconductor wafer of a round type has a curved(semicircular or semi-elliptical) sectional shape as shown in FIG. 1C.

Throughout herein, expression “beveled part” will be used, in the caseof a wafer W of a straight type shown in FIG. 1B, to indicate the uppersloped surface P, the lower sloped surface Q and the end surface R(altogether indicated by letter B), and, in the case of a wafer W of around type shown in FIG. 1C, to indicate the curved surface portionindicated by letter B. Expression “edge” will be used to indicate thesurface portion indicated by letter E between the beveled part B and theportion indicated by letter D for forming a semiconductor device.

FIGS. 2, 3 and 4 show a device 10 according to this invention,comprising a wafer stage unit 20 having a wafer stage 23 for holding awafer W, a stage moving part 30 for transporting the wafer stage unit 20parallel to the surface of the wafer stage 23 and two or more polishingparts for polishing the peripheral edge part of the wafer W held by thewafer stage 23. As representative examples of the two or more polishingparts, the device 10 is shown herein as having a notch polishing part 40for polishing the notch of the wafer W held by the wafer stage 23 andone bevel polishing part 50 for polishing the beveled part of the waferW held by the wafer stage 23, but the invention does not prevent thedevice 10 from having more notch polishing parts or bevel polishingparts. If three notch polishing parts and three bevel polishing partsare provided, the first one of each group of three may be used for roughpolishing, the second for finishing and the third for cleaning.

There is a housing 11, which is divided into two spaces (an upperchamber 15 and a lower chamber 16) by means of a partition plate 14, theupper chamber 15 containing the wafer stage unit 20, the notch polishingpart 40 and the bevel polishing part 50 and the lower chamber 16containing the stage moving part 30.

The housing 11 is provided with an opening 12 on the side surface of itsupper chamber 15. This opening 12 can be opened and closed by means of ashutter 13 adapted to be driven by a cylinder (not shown). The wafer Wis brought into and taken out of the housing 11 through this opening 12.A wafer transporting part of a known kind such as a robot hand (as shownby numeral 13′ in FIGS. 5A and 5B) may be used for transporting thewafer W into and out of the housing 11. The shutter 13 serves tocompletely screen the interior of the housing 11 from the exterior suchthat the degree of cleanliness and the airtight condition of theinterior of the housing 11 can be maintained and that both thecontamination of the wafer from the exterior of the housing 11 and thecontamination of the exterior of the housing 11 due to the polishingliquid and particles that scatter can be prevented.

The device 10 of this invention further comprises a wafer chuck assembly80 for placing the wafer W brought inside the housing 11 onto the waferstage 23 and picking up the wafer W placed on the wafer stage 23 awayfrom the wafer stage 23.

As shown in FIG. 5A, the wafer chuck assembly 80 comprises a first chuckhand 81 having two or more knobs 83, a second chuck hand 82 having twoor more knobs 83, a chuck hand opening part 84 for opening and closingthese first and second chuck hands 81 and 82 parallel to the surface ofthe wafer W held by the wafer stage 23 (in the direction of arrow T1)and a chuck moving part 85 for reciprocatingly moving the first andsecond chuck hands 81 and 82 perpendicularly to the surface of the waferW held by the wafer stage 23 (in the direction of arrow T2) such that,as the first and second chuck hands 81 and 82 are closed, the knobs 83on the first and second chuck hands 81 and 82 will come to contact theperiphery of the wafer W and the wafer W is thus grasped between thefirst and second chuck hands 81 and 82.

As shown in FIG. 5A, the chuck hand opening part 84 comprises a ballscrew b5 which engages the first and second chuck hands 81 and 82, aservo motor m5 for driving the ball screw b5 and a linear guide 87 whichextends in the direction of arrow T1 and penetrates the first and secondchuck hands 81 and 82. The ball screw b5 is connected to a guide 86 anda coupling 89 such that, as the servo motor m5 is operated, the firstand second chuck hands 81 and 82 move in the direction of arrow T1 toopen or close. The center of the wafer W is preferably arranged so as tobe above the center of the wafer stage 23 (or above the rotary shaft Csof the wafer stage 23 to be described below) as the first and secondchuck hands 81 and 82 come to grasp the wafer W in between.

As shown in FIG. 5B, the chuck moving part 85 serves to engage anelevator table 88 attached to the first and second chuck hands 81 and 82with a ball screw (not shown) and to drive this ball screw by means of aservo motor (not shown) so as to move the first and second chuck hands81 and 82 perpendicularly to the surface of the wafer stage 23 (in thedirection of arrow T2). In FIG. 5B, L1 indicates a retracted position,L2 indicates a wafer delivery position where the wafer W on the robothand 13′ is grasped by the first and second chuck hands 81 and 82 or thewafer W is loaded onto the robot hand 13′, and L3 indicates a wafersetting position where the wafer W is set on the wafer stage 23 or thewafer W set on the wafer stage 23 is grasped by the first and secondchuck hands 81 and 82.

As shown in FIGS. 2, 3 and 4, the wafer stage unit 20 further comprisesa stage rotating part for rotating the wafer stage 23 and areciprocating motion part for causing the wafer stage 23 to undergo arotary reciprocating motion with respect to the notch of the wafer Wheld by the wafer stage 23 in the same plane as the surface of the waferW held by the wafer stage 23 (in the direction of arrow R5).

As shown in FIGS. 2-4 and 9, the wafer stage 23 has a flat surfaceprovided with one or more suction holes 25 (only one such suction holein the illustrated example) connected to a vacuum pump (not shown). Anelastic pad 24 having a specified height (thickness) is adhesivelyattached to this surface so as not to block the suction hole 25, and thewafer W is placed on this pad 24. The suction hole 25 is connected to anexternal vacuum pump (not shown) through a hollow shaft 27, a pipe whichis rotatably attached to the lower end of this hollow shaft 27 andanother hollow shaft 31.

Grooves 26 and 26′ connected to the suction hole 25 are formed on theupper surface of the pad 24. Preferably, the pad 24 is formed withconcentric circular grooves 26 and a plurality of radial grooves 26′that connect the circular grooves 26 and these grooves 26 and 26′ areconnected to the vacuum pump referred to above. As the wafer W is placedon the pad 24, these grooves 26 and 26′ are sealed by the lower surfaceof the wafer W in an airtight manner. Thus, if the vacuum pump isactivated, the wafer comes to be supported from its bottom side by thepad 24 without deforming (bending).

The wafer W, thus clasped by the first and second chuck hands 81 and 82,is placed on the pad 24 on the wafer stage 23 by the chuck moving part85. As these chuck hands 81 and 82 are opened by the chuck hand openingpart 84, the vacuum pump is simultaneously activated and the pressure inthe space on the backside of the wafer W (or the interior of the grooves26 and 26′ formed on the upper surface of the pad 24) is reduced,causing it to be pressed towards the pad 24 and to sink somewhat intoit. This is how the wafer W is securely adsorbed to the wafer stage 23and supported by it.

The wafer W thus adsorbed to and supported by the wafer stage 23 isgrasped by the first and second chuck hands 81 and 82 and then lifted upby the chuck moving part 85. When it has floated up a little (say, 0.5mm-1.0 mm), the vacuum pump is stopped and the vacuum suction isstopped. In this manner, there is no instantaneously large force appliedto the wafer W when it is removed from the condition of being adsorbedto the wafer stage 23. In other words, the wafer W can be removed fromthe wafer stage 23 without deforming it or damaging it.

As shown in FIGS. 3 and 4, the stage rotating part comprises a shaft 27that is attached coaxially to the rotary shaft Cs on the backside of thewafer stage 23 and a motor m1 connected to this shaft 27 through apulley p1 and a belt b1. The shaft 27 is rotatably attached through abearing to a support member 22 of a unit main body 21. The motor m1 isaffixed to this supporting member 22. As the motor m1 is activated, thewafer stage 23 rotates around its center, that is, around its rotaryshaft Cs.

The reciprocating motion part is for causing the wafer stage 23 toundergo a rotary reciprocating motion in the same plane as the surfaceof the wafer stage 23 and comprises a shaft 31 which penetrates anopening 17 through the partition plate 14 of the housing 11 at aposition offset from the rotary shaft Cs of the wafer stage 23approximately by the length of the radius of the wafer W and is affixedto the lower surface of the support member 22 of the unit main body 21and a motor m2 connected to this shaft 31 through a pulley p2 and a beltb2. The shaft 31 is rotatably attached to a hollow cylindrical shafttable 29 through a bearing. The lower surface of this shaft table 29 isaffixed to a support plate 32 below the partition plate 14 of thehousing 11, and the upper surface of the shaft table 29 contacts thelower surface of the unit main body 21 to support it. The motor m2 isfastened to this support plate 32. As this motor m2 is activated, thewafer stage unit 20 undergoes a rotary reciprocating motion around arotary shaft Ct within the same plane as the surface of the wafer stage23 (in the direction shown by arrow R5 in FIGS. 2A and 2B). Preferably,the reciprocating motion part causes the wafer stage 23 supporting thewafer W to undergo a rotary reciprocating motion with respect to thenotch of the wafer W within the same plane as the surface of the waferstage 23.

As shown in FIGS. 3 and 4, the stage moving part 30 comprises thesupport plate 32 fastening the shaft table 29 of the reciprocatingmotion part and a parallel motion mechanism for moving this supportplate 32 parallel to the surface of the wafer stage 23.

As shown, the parallel motion mechanism is comprised of a mobile plate33 which is positioned between the partition plate 14 of the housing 11and the support plate 32 and is attached to the partition plate 14through a linear guide 35 so as to be movable in a “first direction”(indicated by arrow X in FIGS. 2A and 4), a ball screw b4 connected tothis mobile plate 33 for moving the mobile plate 33 in the direction ofarrow X, and a motor m4 for driving this ball screw b4. The mobile plate33 has an opening 33′ through which the shaft table 29 passes. Thesupport plate 32 is attached to the lower surface of this mobile plate33 through a linear guide 34 so as to be movable perpendicularly to thefirst direction X (that is, in the direction indicated by arrow Y inFIGS. 2 and 3). A ball screw b3 is connected to the support plate 32 formoving the support plate 32 in the direction of arrow Y and this ballscrew b3 is driven by a motor m3 affixed to the mobile plate 33. Thus,as the motor m4 affixed to the lower surface of the partition plate 14is driven, the ball screw b4 connected to the mobile plate 33 rotatesand the mobile plate 33 moves in the direction of arrow Y, and as themotor m3 affixed to the mobile plate 33 is driven, the ball screw b3connected to the support plate 32 rotates and the support plate 32 movesin the direction of arrow Y with respect to the mobile plate 33. Sincethe ranges of movement of the wafer stage unit 20 in the directions ofarrows X and Y are determined by the size of the opening 17 provided tothe partition plate 14 and the size of the opening 33′ provided to themobile plate 33, the sizes of these openings 17 and 33′ may be increasedat the time of designing the device 10 if larger ranges of movement aredesired for the wafer stage unit 20.

As shown in FIGS. 3 and 10, the notch polishing part 40 is comprised ofa notch polishing head 44 for pressing the notch of the wafer W(hereinafter referred to simply as the notch) to a tape 43 and a tapesupplying part 45 for supplying the tape 43 to the notch polishing head44 and winding up the supplied tape 43. The notch polishing head 44 hasa pair (first and second) of rollers 41 and 42 attached mutuallyparallel to each other with an interval in between such that the notchis pressed against the tape 43 passing between these rollers 41 and 42.The tape supplying part 45 is comprised of a supply roll 46 having thetape 43 wound around it, a take-up roller 47 for taking up the tape 43from the supply roll 46 having the tape 43 from the supply roll 46through the first and second rollers 41 and 42 and a roller driving part(not shown) for driving the take-up roller 47 for taking up the tape 43.

The notch polishing part 40 may also include a mechanism for causing thenotch polishing head 44 to undergo a reciprocating motionperpendicularly to the surface of the wafer W while the tape 43 ispressed against the notch. Although not shown, this mechanism maycomprise a linear guide extending perpendicularly to the surface of thewafer stage 23 and a crank shaft mechanism for moving the notchpolishing head 44 reciprocatingly by means of a motor.

The notch polishing part 40 may further include another mechanism forcausing the notch polishing head 44 to undergo a rotary reciprocatingmotion around the notch (in the direction shown by arrow R3 in FIG. 10)while the tape 43 is pressed against the notch such that the front andback surface sides of the notch can be polished. Although not shown,this mechanism may comprise a shaft extending perpendicularly to thedirection of motion of the tape 43 and a motor for rotating this shaft.This shaft is set at a position where the tape 43 is pressed against thenotch and is connected to the notch polishing head 44, becoming its axisof rotation. As the motor is driven to rotate this shaft, the notchpolishing head 44 undergoes a rotary reciprocating motion in thedirection of arrow R3 around the notch while the tape 43 is pressedagainst the notch such that both its front and back surface sides arepolished.

The notch polishing part 40 may still further be provided with a nozzle48 for supplying the notch with a polishing liquid of a slurry formhaving abrading particles dispersed in water or a water-based reactiveliquid as well as cooling water.

The tape 43 may be of a woven or non-woven cloth or a foamed material. Abase film in the form of a tape made of a plastic material or a tapehaving a polishing layer with abrading particles fastened by means of aresin binder may be used. Examples of abrading particles include diamondparticles with average diameter in the range of 0.1 μm-5.0 μm and SiCparticles with average diameter in the range of 0.1 μm-5.0 μm. Polyesterand polyurethane type resin binders can be used. Examples of base filminclude films of a flexible material such as polyester, polyurethane andpolyethylene terephthalate.

It is preferable to use a tape comprising a polishing layer havingabrading particles affixed by a resin binder together with a polishingliquid having abrading particles dispersed in water and/or coolingwater. This is because the polishing can be effected without using anywater-based reactive liquid and hence the contamination of the water andthe interior of the housing 11 (that is, the contamination of eachconstituent component set inside the housing 11) can be prevented moredependably.

According to practical examples, the width of the tape 43 is within therange of 1 mm-10 mm, the length of the tape 43 is several tens of metersand the tape 43 is wound around a cylindrical core material (shown at46′ in FIG. 8).

The polishing of the notch is carried out by moving the wafer held bythe wafer stage 23 parallel to the surface of the wafer stage 23 by thestage moving part 30 so as to press the notch to the tape 43 of thenotch polishing part 40 and causing the wafer stage 23 to undergo arotary reciprocating motion around the notch (in the direction shown byarrow R5 in FIGS. 2A and 2B) within the same plane as the surface of thewafer W held by the wafer stage 23 by the reciprocating motion part. Inthe above, the notch polishing head 44 may be caused to undergo areciprocating motion perpendicularly to the surface of the wafer Wand/or a rotary reciprocating motion around the notch (in the directionshown by arrow R3 in FIG. 10) while the tape 43 is pressed against thenotch.

Although an example was described above wherein the notch is polished byusing a tape, this is not intended to limit the scope of the invention.The notch may be polished instead by using a disk-shaped pad of a knownkind with the outer periphery not having the same shape as that of thenotch.

As shown in FIG. 8, the notch polishing head 40 may further comprise adiameter detecting part for detecting the outer diameter of the tape 43or the remaining amount of the tape 43 still on the core material 46′ ofthe tape supply roll 46. As shown, this detecting part comprises anoptical sensor having a light emitter 49 a and a light receiver 49 b,the supply roll 46 being preferably disposed between the light emitter49 a and the light receiver 49 b. The outer diameter of the tape 43still wound around the supply roll 46 can be detected by the quantity oflight 49 c received by the light receiver 49 b. The outer diameter ofthe tape 43 thus detected is transmitted to a control device (not shown)for a motor for supplying the tape 43 from the supply roll 46 such thatthe torque value of the motor will vary smoothly and the tension in thetape 43 will remain constant.

As shown in FIGS. 4 and 11, the bevel polishing part 50 comprises abevel polishing head 54 having a cylinder 52 with a contact pad 51attached to its end and a tape supplying part 55 for supplying a tape 53to the bevel polishing head 54 and taking up the supplied tape 53.

The tape supplying part 55 comprises a supply roll 56, a take-up roller57 for winding up the tape 53 from the supply roll 56 through thecontact pad 51 and a driving part (not shown) for driving the take-uproller 57 for winding up the tape 53. The tape 53 passing over thecontact pad 51 is pressed against the beveled part of the wafer Wthrough the contact pad 51 and the beveled part is thereby polished.

The bevel polishing part 50 may also include a mechanism for causing thebevel polishing head 54 to undergo a rotary reciprocating motion arounda beveled part perpendicularly to the surface of the wafer W (in thedirection shown by arrow R4 in FIG. 11). This mechanism may comprise,although not shown, a shaft extending perpendicularly to the directionof motion of the tape 53 and a motor for rotating this shaft. This shaftis set at a position where the tape 53 is pressed against a beveled partof the wafer W and is connected to the bevel polishing head 54, becomingits axis of rotation. As the motor is driven, the bevel polishing head54 undergoes a rotary reciprocating motion around the beveled part inthe direction of arrow R4 while the tape 53 is pressed against thebeveled part such that the front and back surface sides of the beveledpart of the wafer W are polished.

The bevel polishing part 50 may further be provided with a nozzle 58 forsupplying the beveled part with a polishing liquid of a slurry formhaving abrading particles dispersed in water or a water-based reactiveliquid as well as cooling water.

The tape 53 may be a woven or non-woven cloth or a foamed material. Abase film in the form of a tape made of a plastic material or a tapehaving a polishing layer with abrading particles fastened by means of aresin binder may be used. Examples of abrading particles include diamondparticles with average diameter in the range of 0.1 μm-5.0 μm and SiCparticles with average diameter in the range of 0.1 μm-5.0 μm. Polyesterand polyurethane type resin binders can be used. Examples of base filminclude films of a flexible material such as polyester, polyurethane andpolyethylene terephthalate.

It is preferable to use a tape comprising a polishing layer havingabrading particles affixed by a resin binder together with a polishingliquid having abrading particles dispersed in water and/or coolingwater. This is because the polishing can be effected without using anywater-based reactive liquid and hence the contamination of the water andthe interior of the housing 11 (that is, the contamination of eachconstituent component set inside the housing 11) can be prevented moredependably.

According to practical examples, the width of the tape 53 is within therange of 1 mm-10 mm, the length of the tape 43 is several tens of metersand the tape 53 is wound around a cylindrical core material.

If a tape with a polishing layer having abrading particles with averagediameter less than 2.0 μm is used to polish the beveled part of a waferW, it is possible to adjust the diameter of the wafer W to a specifiedlength. If a tape with a polishing layer having abrading particles withaverage diameter 2.0 μm or less is used, a finishing work can be carriedout on the beveled part of the wafer W.

If the average diameter of abrading particles affixed to the polishinglayer is thus selected and the bevel polishing head 54 is caused toundergo a rotary reciprocating motion around the beveled part in thedirection of arrow R4 during the polishing process, it is possible toform the upper and lower sloped surfaces of the wafer W (indicated by Pand Q in FIG. 1B) at any specified angle with a finishing work.

The beveled part of the wafer W is polished by moving the wafer W heldby the wafer stage 23 parallel to the surface of the wafer stage 23 byusing the stage moving part 30, pressing the beveled part of the wafer Wagainst the tape and rotating the wafer stage 23 in the direction ofarrow R1 shown in FIG. 6A by using the stage rotating part. Although anexample using the tape 53 was described above, this is not intended tolimit the scope of the invention. A lapping plate with a pad attached tothe surface or a rotary cylindrical grinding stone of a known type maybe used to polish the beveled part.

The bevel polishing part 50, like the notch polishing part 40, may beprovided with a diameter detecting part for detecting the outer diameterof the tape 54 wound around the supply roll 56. This detecting part islike that for the notch polishing part 40, comprising an optical sensorhaving a light emitter and a light receiver and having the supply rolldisposed between the light emitter and the light receiver. The quantityof light received by the light receiver is measured and the outerdiameter of the tape 53 remaining wound around the supply roll 56 isthereby determined. The outer diameter of the tape 53 thus detected istransmitted to a controller for a motor for supplying the tape 53 fromthe supply roll 56 such that the torque value of the motor will varysmoothly and the tension in the tape 53 will remain constant.

As shown in FIGS. 12A, 12B and 12C, the device 10 according to thisinvention further includes a waterproofing structure for waterproofingthe lower chamber 16 of the housing 11 (and in particular the parallelmotion mechanism contained therein). As shown in FIG. 12A, thewaterproofing structure comprises a hollow semispherical waterproofcover 36 (such as shown in FIG. 12B) having its upper part affixed tothe upper part of the shaft table 29 in a liquid-tight manner and itsbottom part affixed to the periphery of the opening 17 provided to thepartition plate 14 in a liquid-tight manner. Since the shaft table 29moves both in the directions of arrows X and Y, the waterproof cover 36is made of an elastic material in order to prevent damage by the motionof the shaft table 29.

The waterproof cover 36 may be a single structure as shown in FIG. 12Aor a double structure as shown in FIG. 12C. If it is a double structureas shown in FIG. 12C, the partition plate 14 may be provided with anopening 39 connected to an external air pump (not shown) near theopening 17 for blowing in compressed air into the space between theouter cover 37 and the inner cover 38 of the waterproof cover 36 suchthat the outer cover 37 is expanded and water drops gathered on itssurface can be scattered away.

Flexible sheets not permeable to liquids made, for example, of a plasticmaterial are used as the waterproof cover 36 (or outer and inner covers37 and 38). Flexible sheets made of a foamed material may preferably beused.

As shown in FIGS. 6A and 6B, the device 10 of this invention furthercomprises a sensor assembly 90 including a notch position detecting partfor detecting the position of the notch on the wafer W held by the waferstage 23.

The notch position detecting part comprises at least one optical sensor(three sensors 91, 92 and 93 being shown). Each optical sensor may bestructured with a light emitter and a light receiver arranged such thatthe notch N on the watch W being held by the wafer stage 23 passesbetween them. As the wafer W rotates (as shown by arrow R1), light fromthe light emitter is received by the light receiver only when the notchN is directly below the light emitter. This is how the position of thenotch N is detected.

Alternatively, an optical sensor of the straight light regression typemay be used. An optical sensor of this type is a laser sensor having alight emitter and a light receiver disposed on the same side and areflector disposed opposite to them for reflecting the light from thelight emitter. In this case, the laser light from the light emitter isreflected by the reflector and detected by the light receiver only whenthe notch N on the wafer W is passing directly below the light emitterand this is how the position of the notch N is detected.

According to this invention, the rotary motion of the wafer stage 23 isstopped when the position of the notch N is detected as explained abovesuch that the notch N will face the tape of the notch polishing part.

According to the illustrated example, the notch detecting part isprovided with three optical sensors 91, 92 and 93. When the wafer stage23 holding the wafer W is rotating with a rotary speed within a firstrange (such as 12 rpm or slower and 4 rpm or faster), it is the firstoptical sensor 91 that detects the position of the notch N. If the waferstage 23 is rotating at a lower rotary speed within a second range (suchas less than 4 rpm and 1 rpm or faster), it is the second optical sensor92 that detects the notch position. If the wafer stage 23 is rotating ata still lower rotary speed within a third range (such as less than 1rpm), it is the third optical sensor 93 that detects the notch position.

FIG. 14A shows the first optical sensor 91 detecting the notch N passingdirectly below its light emitter, as the wafer stage 23 is rotating at arotary speed within the aforementioned first range. At this moment,light 99 b from the light emitter of the second optical sensor 92 andthe light 99 c from the light emitter of the third optical sensor 93 arescreened by the periphery of the wafer W.

FIG. 14B shows a moment when the wafer stage 23 is rotating at a rotaryspeed within the second range and as the notch N is passing directlybelow the light emitter of the second optical sensor 92 and the notch Nis being detected by the second optical sensor 92. The light 99 a fromthe light emitter of the first optical sensor 91 and the light 99 c fromthe light emitter of the third optical sensor 93 are screened by theperiphery of the wafer W.

Next, FIG. 14C shows a moment when the wafer stage 23 is rotating at arotary speed within the third range and as the notch N is passingdirectly below the light emitter of the third optical sensor 93 and asthe notch N is being detected by the third optical sensor 93. The light99 a from the light emitter of the first optical sensor 91 and the light99 c from the light emitter of the second optical sensor 92 are screenedby the periphery of the wafer W.

In summary, as the wafer wage 23 decelerates until it stops, theposition of the notch N is detected sequentially by the first, secondand third optical sensors 91, 92 and 93 and in a stepwise manner. Thethird optical sensor 93 is adapted to detect the position of the deepestpart of the notch N and hence to detect the position of the notch N mostaccurately within ±0.1°. Since the position of the notch N is detectedmerely while the wafer W is rotationally decelerating in the samedirection, the detection can be made in a short measuring time.

The sensor assembly 90 is provided with a displacement detecting partfor detecting the displacement of the wafer W in its radial direction asbeing held by the wafer stage 23. Such a displacement may be a result ofthe wears on the knobs 83 on the first and second chuck hands 81 and 82.

As shown in FIG. 13A, the displacement detecting part comprises anoptical sensor 93′ having a light emitter and a light receiver disposedsuch that the periphery of the wafer W held by the wafer stage 23 passesbetween the light emitter and the light receiver. As the wafer W isrotated, the optical sensor 93′ detects the change in the quantity oflight received by its light receiver as shown in FIG. 13B and thepositional displacement in its radial direction (indicated by symbol εin FIG. 13A) of the wafer W held by the wafer stage 23.

The displacement may be expressed by using the center (Ch) of the waferW as the origin, and defining a polar coordinate system by using anarbitrary line (r) radially extending therefrom as a referencedirection, in terms of the angle θ from this reference line r and thedistance between the defined origin Ch and the center Cs of the waferstage 23.

As shown in FIG. 13B, the position of the notch is also detected, inaddition to the positional displacement. The aforementioned positionaldisplacement can be detected merely by rotating the wafer W once. InFIG. 13B, the broken line indicates the detected quantity of light whenthe center Ch of the wafer W coincides with the axis of rotation Cs ofthe wafer stage 23, that is, when there is no positional displacement.

FIGS. 6A and 6B show an example wherein the aforementioned third opticalsensor 93 serves as this optical sensor for the displacement detectingpart.

Explained more in detail with reference to FIGS. 14A, 14B and 14C, thethird optical sensor 93 is disposed such that a portion of the light 99c from its light emitter will reach the light receiver and the peripheryinclusive of the notch N of the wafer W held by the wafer stage 23 willpass between the light emitter and the light receiver while the wafer Wis rotating in the direction of arrow R1. As the wafer W rotates, thethird optical sensor 93 detects the changes in the quantity of lightreceived by its light receiver and thereby detects the radialdisplacement of the wafer W adsorbed to the wafer stage 23. When thewafer stage 23 is rotating at a rotary speed in the aforementioned thirdrange, the position of the notch N is further detected.

The sensor assembly 90 further comprises a waterproofing part forpreventing damages to the optical sensors 91, 92 and 93 by the coolingliquid and the polishing liquid used for the tape-polishing of the waferW. As shown in FIGS. 7A and 7B, this waterproofing part comprises anassembly rotating part for rotating the sensor assembly 90 (in thedirection of arrow R2 shown in FIG. 6B) for retracting the opticalsensors from the position of the wafer W and a shutter 94 for coveringthe retracted optical sensors. Although not shown, the assembly rotatingpart is adapted to rotate a shaft affixed to the sensor assembly 90 bydriving a motor. The shutter 94 is adapted to be moved in the directionof arrow T3 as shown in FIG. 7B by means of an air piston to cover theoptical sensors.

The bevel polishing part 50 may further comprise a second displacementdetecting part for detecting the displacement of the wafer W while thebeveled part of the wafer W is being polished. As shown in FIG. 11, thesecond displacement detecting part may comprise a displacement sensor(not shown) for detecting the change in the stretching and shrinking ofa cylinder serving to compress the tape 53 to the beveled part of thewafer W through the contact pad 51 while the wafer W is being polished.As this displacement is detected, it is fed back to the stage movingpart 30 and the displacement of the wafer W in its radial direction iscorrected.

Although not shown, the device 10 according to this invention mayfurther comprise a cleaning part for maintaining the interior of thehousing 11 clean. Such a cleaning part may comprise an air inletprovided to the ceiling of the upper chamber 15 of the housing 11, anair discharge outlet provided to a lower portion on a side surface ofthe upper chamber 15 of the housing 11 and an external pump connected tothis outlet such that the air that flows in through the air inlet willflow inside the housing 11 along its side surfaces. With an air flowthus formed inside the housing 11, particles can be discharged outwardwithout becoming attached to the surface of the wafer W held by thewafer stage 23.

The device 10 according to this invention may further comprise a drynesspreventing part for supplying pure water to the wafer W held by thewafer stage 23 such that the wafer W is prevented from becoming dryafter each time it is polished by the notch polishing part 40 and thebevel polishing part 50 to be transported to the place of the nextprocessing. As shown in FIGS. 2-4, this part comprises nozzles n1 and n2provided inside the housing 11, and pure water is blown out therefromtowards the wafer W being transported. Since pure water is thus suppliedto the wafer W while being transported, not only is the wafer Wprevented from becoming dry but also particles are prevented frombecoming attached to the wafer W.

Although two nozzles n1 and n2 are used according to the illustratedexample, only one nozzle may be provided or more than two of them may beused. The nozzles are positioned such that the wafer W will not collidewith them as the wafer stage 23 is caused to undergo the rotaryreciprocating motion within the same plane as the surface of the waferstage 23.

A method for polishing the peripheral edge part (both the notch and thebeveled part) of a wafer W is explained next.

After the shutter 13 is driven by an air cylinder to open the opening 12on the side surface of the housing 11 and the wafer W is transportedinto the upper chamber 15 of the housing 11 by using the robot hand 13′,the wafer W is brought directly above the wafer stage 23 and the firstand second chuck hands 81 and 82 at the wafer delivery position L2 areused to grasp the wafer W. At this moment, the center of the wafer Wcomes to a position directly above the center of the wafer stage 23which is directly below. Thereafter, the robot hard 13′ is retractedfrom the housing 11 and the shutter 13 is driven by the air cylinder toclose the opening 12 of the housing 11.

While the wafer W remains thus grasped, the first and second chuck hands81 and 82 are lowered to the wafer-setting position L3 and then areopened such that the wafer W is set on the pad 24. The first and secondchuck hands 81 and 82 are raised to the retracted position L1. Thevacuum pump is activated to hold the wafer W, adsorbed onto the waferstage 23.

The sensor assembly 90 is rotated to position the optical sensors 91, 92and 93 on the periphery of the wafer W held by the wafer stage 23, andthe wafer stage 23 is rotated in the direction of arrow R1 to detect theposition of the notch N. While the wafer stage 23 is still rotating, thepositional displacement of the wafer W is also detected.

After the positional displacement of the wafer W is detected, the firstand second chuck hands 81 and 82 are lowered to the wafer settingposition L3 to grasp and lift up the wafer W. The wafer W is releasedfrom the suction force towards the wafer stage 23 by stopping theoperation of the vacuum pump when the wafer W has been lifted up just alittle. The wafer stage 23 is moved by the amount of the detecteddisplacement, and the first and second chuck hands 81 and 82 are loweredto the wafer setting position L3 while grasping the wafer W as describedabove. These chuck hands 81 and 82 are then opened so as to set thewafer W on the wafer stage 23 and the vacuum pump is operated to holdthe wafer W on the wafer stage 23 by suction. Thereafter, the waferstage 23 is rotated as shown by arrow R1 as described above to detectthe position of the notch by means of the optical sensors 91, 92 and 93of the sensor assembly 90 as well as the positional displacement of thewafer W. This process may be repeated until the positional displacementceases to be detected.

Next, the wafer stage 23 is moved towards the notch polishing part 40such that the notch on the wafer W is pressed against the tape 43 of thenotch polishing head 44. While a polishing liquid is supplied to thenotch on the wafer W through the nozzle 48, the tape 43 is caused to runwith the tape 43 remaining pressed against the notch and the wafer stage23 is caused to undergo a rotary reciprocating motion in the directionof arrow R5 around the position of the notch in the same plane as thesurface of the wafer W so as to polish the notch on the wafer W.

The notch is cooled during the polishing process by means of thepolishing liquid supplied to the wafer W and the coefficient of frictionat the notch is reduced. Debris produced by the polishing is preventedfrom scattering around. Although some debris may scatter around,scattered debris is washed off by the polishing liquid and does notbecome attached to the wafer W.

The notch polishing head 44 may be caused to undergo a verticalreciprocating motion or a rotary reciprocating motion (in the directionof arrow R3) to polish the edge E (shown in FIG. 1B) of the notch.

Next, the wafer stage 23 is moved towards the bevel polishing part 50and the beveled part of the wafer W is pressed against the tape 53through the contact pad 51. While the wafer stage 23 is thus moved, purewater is supplied to the wafer W through the nozzles n1 and n2 in orderto prevent it from becoming dry.

The beveled part of the wafer W is polished by causing the tape 53 torun and the wafer stage 23 to rotate while the beveled part of the waferW is pressed against the tape 53 and the polishing liquid is supplied tothe beveled part of the wafer W through the nozzle 58.

The beveled part is cooled during the polishing process by means of thepolishing liquid supplied to the wafer W and the coefficient of frictionat the beveled part is reduced. Debris produced by the polishing isprevented from scattering around. Although some debris may scatteraround, scattered debris is washed off by the polishing liquid and doesnot become attached to the wafer W.

The bevel polishing head 54 may be caused to undergo a verticalreciprocating motion or a rotary reciprocating motion (in the directionof arrow R4) to polish the edge E of the beveled part.

Although an example was shown wherein the polishing of the beveled partis done after the notch is polished, it goes without saying that thenotch may be polished after the beveled part is polished.

The positional displacement of the wafer W may be detected while thebeveled part is being polished. If a displacement is detected, this isfed back to the stage moving part 30 for correcting the positionaldisplacement of the wafer W in its radial direction.

After both the beveled part and the notch are polished, the wafer stage23 is returned to its original position. The first and second chuckhands 81 and 82 are lowered from the retracted position L1 to the wafersetting position L3 to grasp and lift up the wafer W. When the wafer Whas been lifted a little, the vacuum pump is stopped and releases thewafer W from the suctioned condition and the first and second chuckhands 81 and 82 reach the wafer delivery position L2. The air cylinderdrives the shutter 13 to open the opening 12 of the housing 11 and therobot hand 13′ enters the housing 11 and comes to a position below thewafer W. The first and second chuck hands 81 and 82 open such that thewafer W is placed on the robot hand 13′ and is transported out of thehousing 11.

1. A device for polishing the peripheral edge part of a semiconductorwafer, said device comprising: a wafer stage having a surface forholding said semiconductor wafer; a wafer stage unit including a stagerotating part for rotating said wafer stage and a reciprocating motionpart for causing said wafer stage to undergo a rotary reciprocatingmotion in the same plane as said surface; a stage moving part for movingsaid wafer stage parallel to said surface; and two or more polishingparts for polishing the peripheral edge part of said semiconductor waferbeing held by said wafer stage; wherein said reciprocating motion partserves to cause said wafer stage to undergo a reciprocating rotarymotion around an axis that passes through a point on the outer peripheryof said semiconductor wafer such that said semiconductor wafer undergoesa reciprocating rotary motion around a notch on said semiconductorwafer.
 2. The device of claim 1 wherein said two or more polishing partsinclude a notch polishing part for polishing said notch on saidsemiconductor wafer held by said wafer stage and a bevel polishing partfor polishing beveled part of said semiconductor wafer held by saidwafer stage.
 3. The device of claim 1 further comprising a housing thatcontains said wafer stage unit, said polishing parts and said stagemoving part and has a side surface with an opening which can be openedand closed.
 4. The device of claim 3 wherein said housing includes twochambers partitioned by a partition plate, one of said chamberscontaining said wafer stage unit and said polishing parts, and the otherof said chambers containing said stage moving part.
 5. The device ofclaim 1 further comprising a dryness preventing part for supplying purewater to said semiconductor wafer held by said wafer stage.
 6. Thedevice of claim 3 further comprising a chuck assembly for receiving saidsemiconductor wafer transported into said housing, placing saidsemiconductor wafer on said wafer stage and delivering saidsemiconductor wafer on said wafer stage to a wafer transporting part. 7.The device of claim 6 wherein said chuck assembly includes: a firstchuck hand having two or more knobs; a second chuck hand having two ormore knobs; a chuck opening part for opening and closing said firstchuck hand and said second chuck hand; and a chuck moving part forcausing said first chuck hand and said second chuck hand to undergo areciprocating motion perpendicularly to said surface of said waferstage; wherein said knobs contact peripheral parts of said semiconductorwafer when said first chuck hand and said second chuck hand are closedsuch that said semiconductor wafer becomes grasped by said first chuckhand and said second chuck hand.
 8. The device of claim 7 wherein saidchuck opening part comprises a ball screw engaging with at least one ofsaid first and second chuck hands and a servo motor for driving saidball screw wherein said first and second chuck hands open and close assaid servo motor is activated.
 9. The device of claim 1 furthercomprising a sensor assembly having a notch detecting part for detectingthe position of said notch on said semiconductor wafer being held onsaid wafer stage by suction.
 10. The device of claim 9 wherein saidnotch detecting part includes an optical sensor having a light emitterand a light receiver arranged such that said notch on said semiconductorwafer held by said wafer stage by suction passes between said lightemitter and said light receiver, said optical sensor serving to detectthe position of said notch by rotating said semiconductor wafer.
 11. Thedevice of claim 10 wherein said optical sensor is one of three opticalsensors which are first optical sensor, second optical sensor and thirdoptical sensor, said first optical sensor being adapted to detect theposition of said notch when said wafer stage is rotating at a rotationalspeed within a first range, said second optical sensor being adapted todetect the position of said notch when said wafer stage is rotating at arotational speed within a second range that is slower than said firstrange, and said third optical sensor being adapted to detect theposition of said notch when said wafer stage is rotating at a rotationalspeed within a third range that is slower than said second range. 12.The device of claim 9 wherein said sensor assembly further includes adisplacement detecting part for detecting positional displacement inradial direction of said semiconductor wafer held by said wafer stage bysuction, said displacement detecting part comprising an optical sensorhaving a light emitter and a light receiver arranged such that theperipheral edge of said semiconductor wafer held by said wafer stage bysuction passes between said light emitter and said light receiver, saidoptical sensor serving to detect changes in the quantity of lightreceived by said light receiver and to thereby detect a radialdisplacement of the position of said semiconductor wafer held by saidwafer stage by suction.
 13. The device of claim 11 wherein said thirdsensor is arranged such that the peripheral edge including said notch ofsaid semiconductor wafer held by said wafer stage by suction passesbetween said light emitter and said light receiver, said third opticalsensor serving to detect changes in the quantity of light received bythe light receiver thereof and to thereby detect a radial displacementof the position of said semiconductor wafer held by said wafer stage bysuction and to detect the position of said notch of said semiconductorwafer when said wafer stage is rotating at a rotary speed within saidthird range.
 14. The device of claim 9 wherein said sensor assemblyfurther comprises a waterproofing part for waterproofing said sensorassembly.
 15. The device of claim 2 wherein said notch polishing partcomprises: a notch polishing head having a first roller and a secondroller arranged parallel to each other with an interval in between; anda tape supplying part including a supply roll having a tape woundtherearound, a take-up roller for taking up said tape from said supplyroll through said first and second rollers and a driving part fordriving said take-up roller for taking up said tape; wherein said tapeis adapted to be pressed against said notch while passing between saidfirst roller and said second roller to thereby polish said notch. 16.The device of claim 15 wherein said tape comprises a tape-shaped basefilm of a plastic material having a polishing layer with abradingparticles fastened by a resin binder.
 17. The device of claim 15 whereinsaid notch polishing part further includes a mechanism for causing saidnotch polishing head to undergo a reciprocating motion perpendicularlyto said semiconductor wafer while said tape is pressed against saidnotch.
 18. The device of claim 15 wherein said notch polishing partfurther includes another mechanism for causing said notch polishing headto undergo a rotary reciprocating motion around said notch while saidtape is pressed against said notch such that both front and back surfacesides of said notch are polished.
 19. The device of claim 15 whereinsaid notch polishing part further includes a diameter detecting part fordetecting the outer diameter of said tape remaining wound around saidsupply roll.
 20. The device of claim 2 wherein said bevel polishing partcomprises: a bevel polishing head having a cylinder with a contact padattached to an end; and a tape supplying part having a supply rollhaving a tape wound therearound, a take-up roller for winding up saidtape from said supply roll through said contact pad, and a driving partfor driving said take-up roller for winding up said tape; wherein saidtape is pressed against said beveled part while passing on said contactpad and thereby polishes said beveled part.
 21. The device of claim 20wherein said tape comprises a tape-shaped base film of a plasticmaterial having a polishing layer with abrading particles fastened by aresin binder.
 22. The device of claim 20 wherein said bevel polishingpart further includes a mechanism for causing said bevel polishing headto undergo a rotary reciprocating motion around said semiconductor waferwhile said tape is pressed against said beveled part such that bothfront and back surface sides of said beveled part are polished.
 23. Thedevice of claim 20 wherein said bevel polishing part further includes adiameter detecting part for detecting the outer diameter of said taperemaining wound around said supply roll.
 24. The device of claim 20wherein said bevel polishing part further includes a displacementdetecting part for detecting displacement of said semiconductor waferwhile said beveled part is being polished, said displacement detectingpart comprising a displacement sensor for detecting change in stretchingand shrinking of said cylinder serving to compress said tape to saidbeveled part through said contact pad while said semiconductor wafer isbeing polished.
 25. The device of claim 3 further comprising a cleaningpart for maintaining the interior of said housing clean, said cleaningpart comprising an air inlet through an upper surface of said housing,an air discharge outlet through a lower side surface of said housing andan external pump connected to said air discharge outlet, said air inletand said air discharge outlet being arranged such that air flows inthrough said air inlet and flows inside said housing along side surfacesthereof.
 26. The device of claim 4 further comprising a structure forwaterproofing said other chamber.
 27. The device of claim 4 wherein saidpartition plate has an opening; wherein said stage rotating partcomprises a first shaft attached to the center on the back of said waferstage, a support member rotatably attached to said first shaft and afirst motor for rotating said first shaft; wherein said reciprocatingmotion part comprises a second shaft that is affixed to the supportmember of said wafer stage at a position offset from the center of saidwafer stage by approximately the distance of one half of the radius ofsaid semiconductor wafer through said opening through said partitionplate and a second motor for rotating said second shaft, said secondshaft being rotatably attached to a shaft table that is hollow andcylindrical, said shaft table having a lower surface affixed to asupport plate below said partition plate and an upper surface supportingsaid support member by contacting the lower surface of said supportmember and said second motor being affixed to said support member; andwherein said device further comprises a hollow semi-sphericalwaterproofing cover having an upper affixed in a liquid-tight manner toan upper part of said shaft table and a lower part affixed in aliquid-tight manner around said opening through said partition plate,said waterproofing cover being made of an elastic material.
 28. Thedevice of claim 27 wherein said waterproofing cover is of a doublestructure having an inner cover and an outer cover, said device furthercomprising an air supplying part for supplying compressed air into aspace between said inner cover and said outer cover.